The present invention relates to headlight units for motor vehicles.
More particularly, it relates to a headlight unit for a motor vehicle which has a light source and a reflector for concentrating the radiation of the light source on a first lens device which deviates the light beam bundle in an illumination direction from the headlight.
Halogen lamps or gas discharge lamps can be used as light sources. The reflector can be formed as an elliptic mirror or the like. Such a headlight, depending on the construction, can bundle not the total radiation of the light source from the reflector to the lens device and directly use for the illumination purposes. In order to use such a part of the radiation of the light source for illumination purposes which is not bundled by the reflector on the lens device, known headlight units are provided with additional reflector elements for deviating this part of the radiation through the associated dispersion optical element in the illumination direction from the headlight unit and directly for the illumination purposes. With this additional indirectly used radiation, the signal image of the headlight unit can be increased.
While with this approach almost the total radiation of the light source can be used for illumination purposes, it has some disadvantages. The insertion of the additional reflector elements elongates a direct geometrical and spacial extents of the reflector elements to the part of the light beams which is not bundled on the lens device. In other words, in order to produce a predetermined signal image of the headlight unit, the shape and the position of the additional reflector elements must be exactly preselected. There are no free spaces both with respect to the desired signal image and with respect to the shape of the headlight unit.
A headlight unit of the above mentioned general type is disclosed for example in the German patent document DE 32 18 703. The headlight unit disclosed in this reference has a wing-shaped prism discs around the first lens device, in order to make possible the use of the part of the radiation of the light source for the illumination purposes which is not bundled by the reflector to the lens device. The known headlight unit also has the disadvantages that a direct geometrical and spacial relationship of the prims discs to the part of the light beams not bundled on the light device must be provided. In other words, in order to produce a predetermined signal image of the headlight unit, the shape and the position of the wing-shaped prism discs are exactly preselected. Here also a design freedom fails both with respect to the desired signal image and with respect to the shape of the headlight unit.